Cannula system and method for partial thickness rotator cuff repair

ABSTRACT

A trans-soft tissue anchor implantation system in one embodiment includes a positioning wire having a tissue penetrating distal tip, a cannula for passage through the soft tissue and a suture anchor. The cannula has an axial lumen therethrough sized to accommodate at least the positioning wire, a thin-walled distal portion and a tissue engaging feature, such as an arcuate groove, on at least a portion of an outer surface of the cannula proximal of and adjacent to the distal portion. Tissue, such as a tendon, expands into the groove allowing a surgeon to manipulate the tissue with the cannula.

BACKGROUND

The present application relates to systems and methods for performing arepair of soft tissue to bone, particularly a partial thickness rotatorcuff tear.

A common injury, especially among athletes, is the complete or partialdetachment of tendons, ligaments or other soft tissues from bone. Tissuedetachment may occur during a fall, by overexertion, or for a variety ofother reasons. Surgical intervention is often needed, particularly whentissue is mostly or completely detached from its associated bone.Currently available devices for tissue attachment include screws,staples, suture anchors and tacks.

Arthroscopic tissue attachment is commonly practiced in shoulder rotatorcuff and instability procedures utilizing at least one cannula.Typically, an anchor loaded with suture is fixated to bone using aninserter-type device. The suture is normally slidably attached to theanchor through an eyelet or around a post, such that a single length ofsuture has two free limbs. The suture limbs typically are carried alongthe exterior of the inserter, usually within a groove or other exteriorchannel, or within the interior of the inserter. After the anchor isinserted into the bone, one limb of the suture is passed through softtissue to be repaired such as a tendon or labrum. The two ends of thesuture are then tied to each other, thereby capturing the soft tissue ina loop with the anchor. Upon tightening the loop, the soft tissue isapproximated to the bone via the anchor.

A PASTA (Partial Articular Surface Tendon Avulsion, also known asPartial Articular Sided Tendon Avulsion) lesion in a rotator cuff of ashoulder can be particularly difficult to repair. The rotator cuffcomprises a group of muscles which surround the shoulder and tendonswhich attach those muscles to the humeral head. The tendons have afootprint where they attach to the humeral head and, in a PASTA lesion,a portion of the articular side of the rotator cuff tendon's footprintbecomes detached from the humeral head. Such lesions are most commonlyfound on the supraspinatus tendon.

One option for treatment is completion of the partial tear and thencompletion of a repair using standard techniques for a full thicknesstear. Preservation of the existing, healthy tissue attachment is thuslost and the entire tendon must be reattached. Another option includesscrewing a threaded suture anchor through the tendon and into thehumeral head, passing suture through the tendon and tying down thetendon to effect reattachment. This causes further trauma to the tendon.

There has been a long-felt need to provide a surgeon with access throughsoft tissue without excessively damaging the soft tissue. A number ofearly access devices including radially expandable dilators aredisclosed by Dubrul et al. in U.S. Pat. No. 5,431,676. An appliance forforming an opening through skin is described by Jackson et al. in U.S.Pat. No. 4,716,901.

A more recent cannula device is disclosed by Putz in U.S. PatentPublication No. 2003/0073934. Two cannulas having side gaps are alignedwithout the side gaps juxtaposed to define a passage for a probe. Thecannulas are then rotated relative to each other to facilitateseparation from the probe.

It is therefore desirable to have an improved cannula system to minimizetrauma to soft tissue while accessing bone.

SUMMARY OF THE INVENTION

An object of the present invention is to provide improved access to bonethrough soft tissue such as a tendon.

Another object of the invention is to enhance manipulation of the softtissue.

This invention features a trans-soft tissue anchor implantation systemincluding, in one embodiment, a positioning wire having a tissuepenetrating distal tip, a cannula for passage through the soft tissueand a suture anchor. The cannula has an axial lumen therethrough sizedto accommodate at least the positioning wire, a thin-walled, preferablysharp, distal portion and a tissue engaging feature, such as an arcuategroove, indentation or other recess, which is annular in someembodiments, on at least a portion of an outer surface of the cannulaproximal of and adjacent to the distal portion. Tissue, such as atendon, expands into the groove allowing a surgeon to manipulate thetissue with the cannula.

In some embodiments, the system further includes an obturator having adistal tip, which is sharp in one embodiment and is blunt in otherembodiments. Preferably, the obturator includes a central lumen having alongitudinal axis and sized to accommodate the positioning wire, and thedistal tip of the obturator is laterally offset from the longitudinalaxis of the central lumen. Preferably, the offset remains within anominal radius of the central lumen.

Also featured is a cannula having a first curved section having a firstthin-walled distal portion and a second curved section having a secondthin-walled distal portion, the first and second curved sections capableof being moved relative to each other from an initial, low-profileconfiguration, with the second section nesting at least partially withinthe first section to present less than a full circumference of cannulato the soft tissue, to a second, larger configuration defining an axialcannula lumen therethrough.

In certain embodiments, at least one tissue engaging feature such as anarcuate groove is defined on at least a portion of at least one of thefirst and second curved sections. In one embodiment, at least a portionof the tissue engaging feature is protected relative to the tissue inthe initial configuration and is exposed to the tissue in the secondconfiguration. In some embodiments, at least one of the first and seconddistal portions has an angled distal surface to progressively, in aproximal direction extending away from a distal end of that distalportion, increase the surface area of initial contact with and thenpenetration into the soft tissue, and at least one of the first andsecond distal portions has a distal edge which is sufficiently sharp tobe capable of cutting through a tendon.

This invention further features a method for passing a suture anchorthrough a soft tissue and into a bone, by locating a desired anchorreceiving site on the bone, passing a locating wire through the softtissue and at least onto the bone at the anchor receiving site, andpassing over the locating wire and through the soft tissue a cannulawhich comprises a thin-walled distal portion and an axial lumentherethrough sized to accommodate the positioning wire. The methodfurther includes engaging a portion of the soft tissue with a tissueengaging feature on at least a portion of an outer surface of thecannula proximal of and adjacent to the thin-walled distal portion, andthen manipulating the tissue with the cannula. A suture anchor is passedthrough the cannula and placed into the bone at the anchor site.

In some embodiments, the method includes passing the cannula through thetissue while it is in an initial, low-profile configuration with asecond curved section of the cannula being nested within a first curvedsection of the cannula to present less than a full circumference ofcannula to the soft tissue. The first and second curved sections arethen moved relative to each other to a second, larger configurationdefining the axial cannula lumen therethrough. In certain embodiments,the method further includes manipulating the tissue with the cannulaafter the first and second curved sections are moved to the secondconfiguration.

BRIEF DESCRIPTION OF THE DRAWINGS

In what follows, preferred embodiments of the invention are explained inmore detail with reference to the drawings, in which:

FIG. 1 is a perspective view of a novel suture anchor;

FIG. 2 is a side elevation view of the suture anchor of FIG. 1 loadedonto a driver;

FIG. 3 is a top plan view of the suture anchor of FIG. 1;

FIG. 4. is a side elevation view of a humerus and associated rotatorcuff tendon suffering a PASTA lesion showing a K wire being insertedthrough the tendon to a desired location for placing a suture anchor;

FIG. 5. is a side elevation view of the tendon of FIG. 4 showing a novelcannula system being passed through the tendon over the K wire;

FIG. 6 is a perspective view of the cannula system of FIG. 5;

FIG. 6A is an enlarged side view of the distal portion of the cannulasystem of FIG. 6:

FIG. 6B is a cross-sectional view of the cannula system of FIG. 6A;

FIG. 6C is a view similar to FIG. 6B with the K wire removed;

FIG. 7 is a side elevation view of the tendon of FIG. 4 with a sutureanchor loaded onto a driver, such as shown in FIG. 2, being passedthrough the tendon via an outer portion of the cannula system;

FIG. 8 is a side elevation view of the tendon of FIG. 4 showing thesuture anchor implanted into the humerus beneath the tendon and a limbof suture passing from the suture anchor out of an anterior cannula;

FIG. 9 is a side elevation of the tendon of FIG. 4 showing a spinalneedle passed through a location on the tendon and a suture retrieverbeing passed through the spinal needle and out of the anterior cannula;

FIG. 10 is a side elevation of the tendon of FIG. 4 showing both suturelimbs passed from the suture anchor and through the tendon at differentlocations;

FIG. 11 is a side elevation of the tendon of FIG. 4 showing the suturelimbs knotted together to compress the tendon to the humerus thuseffecting repair of the PASTA lesion;

FIG. 12 is a perspective view of a distal portion of an alternativeembodiment of a cannula according to the present invention;

FIG. 13 is a side elevation view in cross-section of the distal portionof the cannula of FIG. 12;

FIG. 14 is a perspective view of an obturator with the cannula of FIG.12;

FIG. 15 is a partial side cross-sectional view of the distal portion ofthe cannula of FIG. 12 passing through and engaging a tendon formanipulation thereof;

FIGS. 16-20 are schematic perspective views of two suture anchors, afterbeing inserted into bone according to the present invention, with suturelimbs being tied through a cannula to fixate a tendon in the shoulder ofa patient;

FIG. 21 is a schematic perspective view of a cannula according to thepresent invention having first and second curved sections which arerotatable relative to each other;

FIGS. 22 and 23 are schematic cross-sectional views of the distalportion of the cannula of FIG. 21 in first and second configurationsrelative to a tendon;

FIGS. 24A-C are schematic underside views of FIGS. 22 and 23; and

FIGS. 25 and 26 are schematic cross-sectional views of the distalportion of an alternative multi-section cannula according to the presentinvention.

DETAILED DESCRIPTION

This invention may be accomplished by a trans-soft tissue anchorimplantation system including, in one construction, a positioning wirehaving a tissue penetrating distal tip, a cannula for passage throughthe soft tissue and a suture anchor. The cannula has an axial lumentherethrough sized to accommodate at least the positioning wire, athin-walled, preferably sharp distal portion and, preferably, a tissueengaging feature, such as an arcuate groove, indentation or otherrecess, on at least a portion of an outer surface of the cannulaproximal of and adjacent to the distal portion. Tissue, such as atendon, expands into the groove allowing a surgeon to manipulate thetissue with the cannula. Cannulas with tissue engaging featuresaccording to the present invention are shown beginning with FIG. 12.Cannulas with first and second curved sections according to the presentinvention, with the second section nesting at least partially within thefirst section to present less than a full circumference of cannula tothe soft tissue, are illustrated beginning with FIG. 21.

FIG. 1 depicts a novel suture anchor 10, for use with a novel cannulasystem and method, with an elongated body 12 having a pointed distal tip14 and a proximal end 16. An axial passageway 18 extends into the body12 from the proximal end 16. The passageway 18 is open along its sides20. A thread 22 encircles the body 12. A suture bridge or post 24, FIG.2, spans the passageway 18 laterally at a distal portion 26 thereof.

Turning also now to FIGS. 2 and 3, an inserter 28 fits into thepassageway 18. A length of suture 30 passes around the suture bridge 24and is received within longitudinal grooves 32 on the inserter 28. Asbest seen in FIG. 3, the cross-sectional shape of the passageway 18 atthe proximal end 16 is essentially a hexagon 34 with a pair of suturepassages 36 on opposite corners thereof. The suture passages 36 lead toeither side of the suture bridge 24. The inserter 28 has a complimentaryshape to fit within the hexagon 34 with its grooves 32 in alignment withthe suture passages 36 on the anchor 10.

The suture anchor 10 as shown with the suture passages 36 penetratingthe body 12 to leave the passageway 18 open except for the thread 22minimizes its cross section to provide the least trauma to soft tissuethrough which it will pass while still having sufficient mechanicalstrength for the driver 28 to drive it into bone. Where additionalfixation strength within the bone may be required the cross section ofthe anchor 10 could be enlarged, in which case the suture passages 36need then not necessarily penetrate the body 12 laterally. The anchor 10can be formed of any suitable biocompatible material such as stainlesssteel, titanium, cobalt chrome, PEEK (polyaryletheretherketone), BiocrylRapide polymer, other biocompatible polymers, polymer-ceramiccomposites, bioabsorbable polymers and the like. Suitable anchormaterials and configurations include those disclosed by Cauldwell et al.in U.S. Patent Publication No. 2008/0147063 and in U.S. Pat. No.7,381,213 by Lizardi, both of which are incorporated herein by referencein their entireties.

FIGS. 4 to 11 illustrate a procedure to repair a PASTA lesion using thesuture anchor 10 of FIG. 1 and a novel cannula system 48. As seen inFIG. 4, either percutaneously or arthroscopically, a Kirschner wire (Kwire) 38, also known as a type of positioning wire or locating wire, isinserted at a first location 39 through a tendon 40 of a rotator cuff toa desired anchor site 42 beneath its attachment footprint 44 andpositioned upon an associated humeral head 46. The K wire 38 can betapped into the bone or merely positioned at the site 42; in otherwords, the wire is positioned at least onto the bone at a desiredlocation. To ease manipulation of the K wire 38 it is preferablytextured on its outer surface and may be provided with a removableproximal handle (not shown). This site 42 on the humeral head 46 iswhere the suture anchor 10, FIG. 1, will be implanted.

As seen in FIG. 5, cannula system 48 is passed over the K wire 38 andthrough the tendon 40 to the site 42. FIG. 6 shows the cannula 48 inmore detail for one construction, with enlargements of the distalportion illustrated in FIGS. 6A-C. Cannula 48 comprises an inner cannula50 having a sharp distal portion 52, proximal handle 54 and a lumen 56therethrough, FIG. 6C. The inner cannula 50 fits within an outer cannula58 which has a distal end 60, proximal handle 62 and lumen 64therethrough. The distal portion 52 of the inner cannula 50 extendsslightly beyond the distal end 60 of the outer cannula 58 and the distalend 60 is tapered so that rather than core through the tendon 40 thedistal portion 52 creates a small hole and the tapering on the distalportion 52 and distal end 60 allow the cannula system 48 to push asidethe tissue and create the smaller hole through the tendon 40 with theleast damage thereto, in other words, with less cutting of soft tissue.Prior cannulas were inserted through a slit cut into the tissue. Thecannula system 48 dilates the tissue gently to minimize trauma to thetissue. The outer cannula 58 has lines 66 which provide a visualindication of depth penetration and also a visualization window 68 whichaids in anchor insertion and assessment of appropriate depth into thebone. To prevent slippage of the inner cannula 50 relative to the outercannula 58 during insertion so provision is preferably provided to helpkeep them together. Shown are an interlocking nub 70 and groove 72, butother options such as a friction fit, threading, or magnets are employedin other constructions.

As seen in FIG. 7, in preparation for insertion of the anchor 10, the Kwire 38 and inner cannula 50 are removed leaving the outer cannula 58positioned at the anchor site 42. The suture anchor 10 is preloaded ontothe inserter 28, with the suture 30 in place around the suture bridge 24and passing through the suture passages 36 and grooves 32 (see FIG. 2),is passed down through the outer cannula lumen 60 to the anchor site 42and is then driven into the humeral head 46. If the anchor 10 is formedof a biocompatible metal such as stainless steel or titanium it can besimply twisted in via the inserter 28. If instead it is formed of abioabsorbable polymer or other material having less strength a pilothole should be prepared such as with a drill, tap or awl, at the site 42through the cannula 46 prior to inserting the anchor 10 through thelumen 60. The inserter 28 and outer cannula 58 can then be removedleaving first and second suture limbs, 74 and 76 respectively, passed upthrough the tendon 40 at the first location 39 through which the cannula48 had passed. As seen in FIG. 8, the first suture limb 74 is thenretrieved through an auxiliary cannula 78 such as via a grasper (notshown).

As seen in FIG. 9 a spinal needle 80 is passed through the tendon 40 ata second location 82 spaced apart from the first location 39. A flexiblewire suture capture device 84 having a suture capture loop 86 (such as aChia Percpasser available from DePuy Mitek, Inc. of Raynham, Mass.) ispassed through the spinal needle 80 and retrieved out through theauxiliary cannula 78 so that the first suture limb 74 can be threadedthrough the suture capture loop 86. When the spinal needle 80 and suturecapture device 84 are pulled back through the skin this pulls the firstsuture limb 74 through the tendon 40 at the second location 82. For aquick procedure, the first and second suture limbs 74 and 76 could nowbe knotted together tying down the tendon 40. However, it is preferableto repeat the procedure of FIGS. 8 and 9 with the second suture limb 76to pass it through the tendon 40 at a third location 88 on an oppositeside of the first location 39 as shown in FIG. 10. To ease in knot tyingboth suture limbs 74 and 76 are preferably pulled out through a singleportal such as the auxiliary cannula 78 or other portal through theskin. A knot 90 can then be tied and pushed down to tightly secure thetendon 40 to the humeral head 46 as shown in FIG. 11. By passing thesuture limbs 74 and 76 through the tendon 40 at locations 82 and 88 onopposite sides of the first location 39 and defect caused at thatlocation via the passing of the cannula system 48 will be naturallypulled together when the knot 90 is tightened.

Depending upon the extent of the PASTA lesion it may be desirable toplace more than one suture anchor 10 beneath the tendon 40. In such casethe suture limbs therefrom can be tied together. It would still bepreferable to pass the suture limbs through the tendon at separatelocations as illustrated in FIGS. 9 and 10 prior to tying them together,preferably in a mattress pattern. One procedure utilizing two sutureanchors is illustrated in FIGS. 16-20 below. Also, a repair could befashioned employing one or more knotless suture anchors (not shown) suchas disclosed in U.S. Published Application No. 2008/0033486 by Whittakeret al., incorporated herein by reference in its entirety, placed at alocation 92 laterally of the tendon 40 and wherein the suture limbs 74and 76 from the one or more anchors 10 can be passed in a dual rowprocedure, preferably also employing a mattress pattern. If a lateralanchor is employed, one such method is to put the a pair of presentsuture anchors 10 anterior and posterior and have one limb 74 from eachtied to each other and the other limbs 76 spanned to the lateral anchor,preferably knotless, such that it forms a triangle.

The suture anchor 10 and cannula system 48 may also be used to effectrepair of a SLAP (Superior labral tear from Anterior to Posterior)lesion. Typically a much larger traditional cannula (7-8 mm) is placedthru the rotator cuff to access the superior labrum for a SLAP repair.The present cannula system is much smaller and also due to its tendencyto dilate the tissue rather than be inserted through a large slit wouldinflict less trauma to the rotator cuff. Such a procedure may be asfollows: insert the K wire 38, and then the cannula system 48 in thefashion heretofore described through the rotator interval; drill a holein the glenoid rim; insert the anchor 10; remove the cannula system 48;pass suture through the labrum using a suture shuttle; and tie knots.

The procedure is conveniently performed through a cannula system 48which provides both access through the skin and through the tendon 40.The cannula system 48 is sized to just pass the anchor 10, not leavingmuch room for passing instruments to manipulate the tissue, especiallythe tendon 40. Although described in reference to the optimally narrowsuture anchor 10, the cannula system 48 and method of penetrating softtissue for anchor placement therewith are suitable for other anchors oflarger size, as are other constructions of cannulas according to thepresent invention. For instance they could be employed with the HEALIXor GRYPHON anchors in sizes 4 mm and above available from DePuy Mitek,Inc. of Raynham, Mass.

FIGS. 12 and 13 show a distal portion 200 of an alternative embodimentof a cannula 202 according to the present invention which incorporatesan ability to manipulate the tendon (not shown in FIGS. 12 and 13). Atleast the distal portion and shaft of cannula 202 are formed of amedical-grade, sterilizable metal such as a stainless steel material.The leading edge of distal portion 200 is ground on the outside toprovide a slight annular chamfer 204 and create a sharp distal edge 206,preferably sufficiently sharp to be capable of cutting through a tendon.It is also asymmetric to assist in penetrating tissue. A first angle208, preferably about 20 degrees, is ground across the portion 200 tocreate a sharper tip 210. A second angle 212, preferably about 45degrees, is ground across a proximal portion of angle 208 to create apair of points 214 which can engage the bone and help hold the distalportion 200 in position thereagainst. It can also assist in providingsome cutting action if needed, especially if the cannula 202 is rotatedas it is passed through tissue. An annular groove 215 about the outersurface of the cannula 202 sits proximal of the distal portion 200 andprovides for tissue engagement which will be shortly explained. The term“groove” is intended to include elongated depressions, channels andother recesses.

Turning also now to FIG. 14, an obturator 216 is sized to fit closelywithin the cannula 202 and mates with enlarged proximal collar or handle203 of cannula 202 in this construction. Obturator 216 has a centralaxis 218 and terminates in a distal tip 220 which is laterally offsetfrom the central axis 218 and is sharp in some constructions and bluntin other constructions. A central lumen 222 passes down the obturator216 for receiving the K-wire (not shown in FIGS. 12-14). By making thetip 220 off-axis it is not interrupted by the lumen 222.

In practice, the cannula 202 and obturator 216 work similarly to theprocedure described above. A K-wire, preferably with a trocar-type tip,is placed through the skin and tendon to engage the underlying bone atthe position for placing the anchor (not shown in FIGS. 12-14). Thecannula 202 with the obturator 216 therein and its distal tip 220extending distally thereof is passed over the K-wire. The obturatordistal tip 220 mostly dilates tissue as in passes along the K-wire,especially when distal tip 220 is blunt, and the chamfer 204 of cannula202 likewise further dilates the tissue. Accordingly, the cannula 202and obturator 216, rather than cut a cannula-sized hole out of thetissue, expand an opening through it while removing little tissue tocreate less damage to the tissue and ease healing of the tissue afterthe procedure.

Turning also now to FIG. 15, once the cannula 202 has penetrated thetendon 40 the groove 215 provides an engagement with the tendon 40 whichtends to expand slightly into the groove 215, such as illustrated bytissue bulge 217, and catch sufficiently, yet gently, on the cannula 202such that a surgeon can lift the tendon to enhance visualization of thebone underneath without damaging the tendon. The tendon 40 can be movedacross the bone to a desired position if the surgeon wishes. Theprocedure is then completed as described above with an anchor beingplaced through the cannula 202. In other constructions, the tissueengaging feature is a raised rib or other projection. However, a type ofgroove is preferred instead of a projection to minimize trauma to thesoft tissue. A projection may further dilate the tissue, and less tissuedilation is generally preferred.

FIGS. 16-20 illustrate an alternative technique for repair of shoulder Sutilizing at least two suture anchors 302 and 310, each of whichpreferably has been inserted through tendon T and into humerus bone H attwo desired locations utilizing procedures described above. Anchor 302slidably carries suture limbs 304 and 306 while anchor 310 carriessuture limbs 312 and 314. An arthroscope (not shown) is placed in thesubacromial space above the head of humerus H. Cannula 300, FIG. 16, isinserted laterally in the same portal used for subacromialdecompression. One suture limb is retrieved through cannula 300 fromeach anchor, such as limbs 306 and 312, FIG. 17. A clamp 320 is placedon suture limbs and a knot 321 is tied against clamp 320. The knot 321is then shuttled through cannula 300, as indicated by arrow 322, FIG.18, by pulling on the other suture limbs 304 and 314 as indicated byarrows 324 and 326, respectively, until a desired tension on tendon T isachieved. Suture limbs 304 and 314 are then tied arthroscopically usinga non-sliding knot to complete the repair with a suture bridge 330, FIG.20, to fixate tendon T to humerus H. Excess suture may be removed with acord cutter as desired.

Other systems according to the present invention ease insertion of acannula through soft tissue by creating a small initial incision whichis then expanded to create a portal, preferably trans-tendonous, to thedesired repair location. Preferably, the cannula has multiple curvedportions or sections which interact with one another to insert throughtissue in a minimally invasive fashion and then are rotated or otherwisemanipulated to create a full portal through soft tissue as desired.

In some constructions, a cannula system according to the presentinvention has multiple interacting thin-walled, preferably sharp-tippedsleeves, cylinders or tubes, also referred to as curved sections, whichare partial-arcs in some constructions and substantially full-arc,full-circumference cylinders in cross-section spaced from their distalportions in other constructions. In an initial configuration, the distalportions of the tubes are aligned to present less than a fullcircumference of cannula to the soft tissue, such as to form asemi-circle, preferably substantially a half-circle or less, andinserted through soft tissue to form a “half-moon”-like, crescent-shapedincision or opening through the soft tissue. The cannula tubes are thenmanipulated to form a substantially circular portal through the softtissue. Suture anchors or other devices or instruments can then bepassed through the cannula system. After use is completed, the systempreferably is collapsed or otherwise returned to its initialconfiguration and removed from the patient while minimizing trauma tothe soft tissue. An initial low-profile, relatively small incision isthereby dilated by manipulating the cannula to form an arthroscopicportal.

Cannula 400 according to the present invention, shown in an initial,low-profile configuration in FIGS. 21 and 22, has a first curved outersection 402 and a second curved inner section 404 which is generallycoaxial with first section 402. Preferably, at least the shafts anddistal portions of sections 402 and 404 are formed of a medical-grade,sterilizable metal such as a stainless steel material. A grip 406 ofbiocompatible material is positioned near the proximal end of firstsection 402 and a grip 408 is positioned near the proximal end of secondsection 404 to assist rotation, either manual or robotic, of thesections 402, 404 relative to each other as indicated by arrows 410 and412. A proximal opening 414 is defined in second section 404 tocommunicate with an axially-extending cannula lumen 420. First section402 has an angled or tapered distal portion 422 terminating in a distalend 426 with a beveled edge 427, shown in enlarged cross-section inFIGS. 22 and 23, and second section 404 has an angled or tapered distalportion 424 terminating in a distal end 428 with a beveled edge 429. Inthis construction, edges 427 and 429 are sufficiently sharp to becapable of cutting through a tendon. Also in this construction, bothdistal portions 422 and 424 define arcuate grooves 430 and 432,respectively.

First and second sections of cannula 400 are shown in the initialconfiguration in FIGS. 22 and 24A relative to tendon T and in a second,expanded configuration in FIGS. 23 and 24B. Both the first and seconddistal portions progressively increase arcuately as measurableprogressing away from distal ends 426 and 428, that is, both distalportions 422 and 424 have an angled distal surface to progressivelyincrease the surface area of initial contact with the soft tissue.Tissue engagement feature 432 is covered in the initial configurationand is exposed in the expanded configuration to enhance contact withtendon T to facilitate manipulation of that tissue by a surgeon.

Preferably, sections 402 and 404 are returned to the initialconfiguration after access through and manipulation with cannula 400 hasbeen completed, as illustrated in FIG. 24C. Further trauma to the softtissue is thereby minimized as the cannula 400 is withdrawn from apatient.

Alternative cannula 500 is shown in an initial configuration in FIG. 25and in an expanded configuration in FIG. 26 having first curved section502 and second curved section 504. In this construction, soft tissue Tis fully dilated by the initial configuration as cannula 500 is passedthrough tissue T. While both the first and second distal portions 522and 524 have an angled distal surface to progressively increase thesurface area of initial contact with the soft tissue, only the seconddistal end 528 has a beveled edge in this construction. First distal end526 is simply thin-walled.

Cannula systems according to the present invention have been describedherein for use with rotator cuff repair including PASTA repairs andlesion repairs including SLAP repairs, but those are not limitations ofthe invention. Other suitable procedures for shoulder repair includebiceps tenodesis, Bankart repair, acromio-clavicular separation repair,deltoid repair, capsular shift and capsulo-labral reconstruction.Suitable foot and ankle procedures include lateral stabilization, medialstabilization, Achilles tendon repair, mid-foot reconstruction, halluxvalgus repair, metatarsal ligament and tendon repairs. Suitable kneeprocedures include medial collateral ligament repair, lateral collateralligament repair, posterior oblique ligament repair, and ilio-tibial bandtenodesis. Suitable elbow repairs include biceps tendon reattachment,ulnar and radial collateral ligament reconstruction, and lateralepicondylitis repair. Suitable wrist procedures include scapholunateligament reconstruction, and suitable hip procedures include capsularrepair and acetabular labral repair.

While the invention has been particularly described in connection withspecific embodiments thereof, it is to be understood that this is by wayof illustration and not of limitation, and that the scope of theappended claims should be construed as broadly as the prior art willpermit. Thus, while there have been shown, described, and pointed outfundamental novel features of the invention as applied to a preferredembodiment thereof, it will be understood that various omissions,substitutions, and changes in the form and details of the devicesillustrated, and in their operation, may be made by those skilled in theart without departing from the spirit and scope of the invention. Forexample, it is expressly intended that all combinations of thoseelements and/or steps that perform substantially the same function, insubstantially the same way, to achieve the same results be within thescope of the invention. Substitutions of elements from one describedembodiment to another are also fully intended and contemplated. It isalso to be understood that the drawings are not necessarily drawn toscale, but that they are merely conceptual in nature. It is theintention, therefore, to be limited only as indicated by the scope ofthe claims appended hereto.

Every issued patent, pending patent application, publication, journalarticle, book or any other reference cited herein is each incorporatedby reference in their entirety.

What is claimed is:
 1. A method for passing a suture anchor through atendon and into a bone, the method comprising the steps of: locating adesired anchor receiving site on the bone; passing a locating wirethrough the tendon and at least onto the bone at the anchor receivingsite; passing over the locating wire and through the tendon a cannulawhich comprises a thin-walled distal portion, and an axial lumentherethrough sized to accommodate at least the positioning wire;engaging a portion of the tendon with a tissue engaging feature on atleast a portion of an outer surface of the cannula proximal of andadjacent to the distal portion and then manipulating the tendon with thecannula; passing the suture anchor through the cannula and placing thesuture anchor into the bone at the anchor site; and wherein the step ofmanipulating the tendon comprises lifting the tendon away from the bone.2. The method according to claim 1 wherein the step of manipulatingcomprises moving the tendon to enhance visualization underneath thetendon.
 3. The method according to claim 1 and further comprising thestep of attaching the tendon to the bone via a suture attached to thesuture anchor.
 4. The method according to claim 1 wherein the tendon isa rotator cuff tendon.
 5. A method for passing a suture anchor through atendon and into a bone, the method comprising the steps of: locating adesired anchor receiving site on the bone; passing a locating wirethrough the tendon and at least onto the bone at the anchor receivingsite; passing over the locating wire and through the tendon a cannulaincluding a first curved section having a first thin-walled distalportion and a second curved section having a second thin-walled distalportion, the first and second curved sections being positioned relativeto each other in an initial, low-profile configuration with the secondsection nesting at least partially within the first section to presentless than a full circumference of cannula to the tendon; moving thefirst and second curved sections relative to each other from theinitial, low-profile configuration to a second, larger configurationdefining an axial cannula lumen therethrough; and passing the sutureanchor through the cannula and placing the suture anchor into the boneat the anchor site.
 6. The method according to claim 5 wherein thecannula further includes a tissue engaging feature on an outer surfaceof at least one of the first and second curved sections of the cannulaproximal of and adjacent to the distal portion, and the method furtherincludes engaging a portion of the tendon with a tissue engaging featureon an outer surface of the cannula proximal of and adjacent to thedistal portion and then manipulating the tissue with the cannula.
 7. Themethod according to claim 6 wherein at least a portion of the tissueengaging feature is protected relative to the tissue in the initialconfiguration and is exposed to the tissue in the second configuration.8. The method according to claim 6 wherein the tissue engaging featureis an arcuate groove on each of the first and second curved sections. 9.The method according to claim 6 wherein the tissue engaging featurecomprises a groove.
 10. The method according to claim 6 wherein the stepof manipulating the tendon comprises lifting the tendon away from thebone.
 11. The method according to claim 5 wherein at least one of thefirst and second distal portions has an angled distal surface toprogressively increase the surface area of initial contact with thetendon.
 12. The method according to claim 5 wherein at least one of thefirst and second distal portions has a distal edge which is sufficientlysharp to be capable of cutting through the tendon.
 13. The methodaccording to claim 5 and further comprising the step of attaching thetendon to the bone via a suture attached to the suture anchor.
 14. Themethod according to claim 5 wherein the tendon is a rotator cuff tendon.15. The method according to claim 5 wherein the step of moving the firstand second curved sections relative to each other comprises rotating atleast one of the first and second curved sections about a longitudinalaxis through the cannula.
 16. A method for passing a suture anchorthrough a tendon and into a bone, the method comprising the steps of:locating a desired anchor receiving site on the bone; passing a locatingwire through the tendon and at least onto the bone at the anchorreceiving site; passing over the locating wire and through the tendon acannula which comprises a thin-walled distal portion, and an axial lumentherethrough sized to accommodate at least the positioning wire;engaging a portion of the tendon with a tissue engaging feature on atleast a portion of an outer surface of the cannula proximal of andadjacent to the distal portion and then manipulating the tendon with thecannula; passing the suture anchor through the cannula and placing thesuture anchor into the bone at the anchor site; and wherein the tissueengaging feature comprises a groove.